Metabolic syndrome is a cluster of cardiovascular risk factors. Pathogenesis of metabolic syndrome implies 3 potential etiological mechanisms: obesity and adipose tissue disorders, insulin resistance, and a constellation of independent factors. Clinical recognition of the metabolic syndrome is based on finding several well-recognized signs in clinical practice: abdominal obesity, elevated triglycerides, reduced HDL cholesterol, raised blood pressure, and elevated plasma glucose. In addition, other components commonly aggregate with the major components: elevated apolipoprotein B, small LDL particles, insulin resistance and hyperinsulinemia, impaired glucose tolerance (IGT), elevated C-reactive protein (CRP), and variation in coagulation factors (plasminogen activator inhibitor [PAI]-I and fibrinogen). Cardiovascular disease (CVD) is the primary clinical outcome of metabolic syndrome. Additionally, risk for type 2 diabetes is higher. Diabetes is itself a major risk factor for CVD. ATP III criteria for diagnosis of metabolic syndrome provide a practical tool to identify patients at increased risk for CVD. World Health Organization (WHO) and American Association of Clinical Endocrinologists (AACE) criteria require further oral glucose testing if IFG and diabetes are absent. IGT on OGTT denotes greater risk for diabetes than does metabolic syndrome without elevated fasting glucose.